The electroencephelogram-based technology Capita acquired from NASA was, compared to the way it appears and works today, quite rudimentary. The device the space agency used to read crew members brainwaves looked like a shower cap with grommets on it. To get clear readings a conductive gel had to be injected into the grommets with a hypodermic needle, while the pilot was wearing the cap.

Two and a-half years later, the cap has been re-engineered so that now it is about the size, weight, and appearance of a pair of headphones for a portable tape or CD player. It takes a few seconds to fit the headset to an individual so that the sensors are in the correct position to pick up the necessary readings. The procedure is dry and noninvasive.

Readings from the headset are transmitted to a computer powered by Capita's proprietary software. The computer reads the electrical signals coming from the surface of the scalp five times a second, converting those signals into a scrolling graph that is synchronized with the visual stimuli, such as television programming, commercial advertisements, web sites, or print materials.

Peaks and valleys in the graph correspond to when the viewer is engaged or tuned out.